The present invention relates to watercraft lifting systems; more particularly, the present system pertains to watercraft lifting systems which are mounted between substantially parallel docks between which small watercraft are typically stored. Such arrangements of docks are often found on lakes, inlets, marinas and canals or other waterways used by small recreational watercraft.
In many locations where small watercraft are stored it has become desirable and sometimes necessary to lift these small watercraft out of the water. A variety of methods are being used to meet this need.
In the following description the word "boat" will be used; however, it will be understood that this word will be meant to include such other watercraft as Jet-Skis.RTM., pontoon boats and the like.
Typically prior art small boat lifting systems incorporate a boat cradle which is placed between the substantially parallel dock members. The small boat is first caused to rest upon the boat cradle. Then the boat cradle is guided upwardly to lift the boat from the water by a guide assembly mounted within the substantially parallel dock members. The actual lifting of the boat cradle from the water is accomplished by flexible cables. These flexible cables pass around a complex system of pulleys and are then wound around a cable reel located at the head of the dock assembly. Such boat lifting systems place inordinately large stresses on the cables. It has been found that such cables repeatedly fail because of the stresses caused by high boat loads and the many twists and turns taken by the cables before being wound on a cable reel. In addition, such boat lifting systems are also expensive because of the need to install a guide assembly in the docks on either side of the boat to guide the boat lifting cradle in its travel upwardly out of the water.
There is therefore a need in the art to provide a boat lifting system which is simple, inexpensive and reliable. Such boat lifting system should be easy to use and easy to install without requiring major disassembly or reconstruction of the docks between on which it is to be installed.
A prior art search was done and the following patents were identified; U.S. Pat. Nos. 3,073,125, 3,114,246, 3,276,211, 4,329,082, 4,686,920.
Exemplary of systems using complex cable arrangements which place large forces on such cables and cause quick wear of cables are those shown in U.S. Pat. Nos. 3,114,246 and 4,329,082.
Systems designed for larger boats which employ flexible cables are found in U.S. Pat. Nos. 3,073,125 and 3,276,211.
U.S. Pat. No. 4,686,920 illustrates an extremely complex cable system used for lifting small boats from the water. Because of the number of twists and turns made by the cable in the system disclosed in U.S. Pat. No. 4,686,920 it is anticipated that, while operative, this system is subject to frequent failure because of the stresses put on the lifting cables.